1. Field of the Invention
The present invention relates to a ceramic capacitor and a process for producing the same, and particularly, to a ceramic capacitor with a joining or bonding layer having an improved heat resistance in a lead type chip capacitor and a process for producing the same.
2. Description of the Prior Art
One of electronic parts carried on an electronic apparatus is a ceramic capacitor which is produced by laminating a ceramic dielectric material and an internal electrode. A lead type chip capacitor often comprises a lead terminal 1 mounted at each of opposite ends of a capacitor chip 3 with a joining or bonding layer 2 interposed therebetween, as shown in FIG. 1. The capacitor chip 3 is comprised of a ceramic dielectric material 31 and an internal electrode 32.
For the joining or bonding layer 2 in the lead type chip capacitor, solders having lower melting points have been conventionally used such as Pb-Sn , Pb-Ag and Bi-Sn alloys, any of which have a melting point lower than 400.degree. C. Capacitors having a terminal electrode made of a material such as Ag or Ag/Pd include those having a lead terminal 1 connected by use of a higher melting solder.
Because any of these solders has a melting point lower than 400.degree. C. as described above, however, the following troubles have been often encountered: In soldering the lead terminal 1 for mounting onto a circuit substrate, heat may be transmitted through the lead terminal 1 to heat and melt the joining layer 2. As a result, the lead terminal 1 bonded to the joining layer 2 may be peeled off, or when an electronic apparatus having a lead type chip capacitor mounted thereon is in service, a circuit may be heated to a higher temperature, with a result that the lead terminal 1 bonded to the joining layer 2 may be likewise peeled off.
Further, when a high melting solder is used, there is a fear that heat causes a mechanical stress to be applied to a capacitor chip, whereby the latter may be broken.